Certain disease states require treatment using one or more different medicaments. Some drug compounds need to be delivered in a specific relationship with each other in order to deliver the optimum therapeutic dose. Here, combination therapy may be desirable, but not possible in a single formulation for reasons such as, but not limited to, stability, compromised therapeutic performance and toxicology.
For example, in some cases it might be beneficial to treat a diabetic with a long acting insulin and with a glucagon-like peptide-1 (GLP-1), which is derived from the transcription product of the proglucagon gene. GLP-1 is found in the body and is secreted by the intestinal L cell as a gut hormone. GLP-1 possesses several physiological properties that make it (and its analogs) a subject of intensive investigation as a potential treatment of diabetes mellitus. Another example of a medicament combination is the administration of a pain reliever in combination with a medicament for treating osteoarthritis.
Drug delivery devices of the aforementioned kind often have applications where regular injection by persons without formal medical training occurs. This is increasingly common among patients having diabetes or the like, e.g. osteoarthritis. Self-treatment enables such patients to conduct effective management of their disease. In combination therapy, a primary medicament and a secondary medicament are delivered in a specific relationship to deliver the optimum therapeutic dose.
In some cases, depending on the patient or the stage of the therapy, an effective treatment requires variations in the quantities and/or proportions of the medicaments making up the combined therapy. For example, the patient may require a non-adjustable fixed dose of the secondary medicament in combination with an adjustable variable dose of the primary medicament.
The effectiveness of a combined delivery of medicaments may require one or more doses to be delivered sequentially with one of the two medicaments being injected into the human body prior to the delivery of the other medicament. Such treatment may be conducted with devices that include two separate dispensing mechanisms in one injection or drug delivery device that are actuated independently from each other such that the dispensing mechanisms are activated successively. The primary medicament, e.g. a long-acting insulin, is stored in a primary cartridge, while the secondary medicament, e.g. GLP-1 is stored in a separate secondary cartridge. The device comprises two separate dispense rods, such as lead screws, piston rods or the like. The dispense rods have a distal end respectively, which is usually equipped with a bearing or the like to move a bung in the respective cartridge towards a dispensing end such that the respective content of the cartridge is dispensed. For the injection, both cartridges may be connected to a common needle hub with a single injection needle. Some kinds of drug delivery assemblies comprise a compartment such as one or more cartridge holders for respectively accommodating a replaceable medicament container such as a cartridge which stores the respective medicament.
The separate actuation of the dispense mechanisms is often expensive. The user is required to set and dispense the required dose of the primary medicament with the first dispense mechanism and to set and dispense the required dose of the secondary medicament with the second dispense mechanism. Sometimes patients require merely a dose of one of the medicaments, e.g. the primary medicament without a dose of the secondary medicament. Overall, the correct use of the device may be hazardous for patients that are physically or mentally impaired or otherwise disadvantaged. Patients may forget to set the device for injection of one of the medicaments, which includes a significant risk to the user. There is also the risk of operating errors. For example, the user may set a wrong dose of the secondary medicament, which may have a negative effect on the treatment. As effective therapy treatment may also require a strict order in the dispense sequence, in which one the medicaments is dispensed prior to the other of the medicaments, the operation of the device may be challenging, as well.